1. Field of the Invention
This invention relates to setting tools of packers, and more particularly, to a setting tool which is hydraulically actuated and has a built-in fill valve.
2. Description of the Prior Art
In the drilling or reworking of oil wells it is often desirable to seal between one oil well flow conductor, such as tubing or other pipe, and another flow conductor, such as the well casing in which the tubing is telescoped. Such a seal is generally provided by a packer.
One particular type of packer which is known to the prior art is a squeeze packer. A squeeze packer includes a mandrel having upper and lower slip assemblies connected thereto with expandable packer elements located between the slip assemblies. A tension sleeve is threadedly engaged with an upper end of the packer mandrel. The packer includes a valve means such as an internal sliding sleeve located within a bore of the packer mandrel.
Such a squeeze packer has previously been actuated by a tool known as a setting tool. Some setting tools of the prior art operate purely mechanically and include a stinger means or lower mandrel for engagement with the sliding valve sleeve, a tubular setting sleeve for engagement with the upper slip assembly of the packer to set the upper slip assembly, drag springs connected to the setting sleeve, and a screw jack means for producing axial motion of the setting sleeve relative to the stinger means when a drill string to which the setting tool is attached is rotated. Prior art setting tools have also included threaded connections to the tension sleeve of the packer. Squeeze packers are operated by the setting tools in the following manner.
A setting tool is made up to the end of a tool string. The packer is threadedly connected to the setting tool. Then, the tool string, setting tool and packer are run into the oil well casing until the desired location of the packer is reached.
The tool string is then rotated a predetermined number of revolutions, thereby moving the setting sleeve downwardly relative to the stinger means so that the setting sleeve engages the upper slip assembly of the packer to set the upper slip assembly against the inner bore of the casing.
After the upper slip assembly is set, the drill string is pulled upwardly to expand the packer elements and to set the lower slip assembly. After the lower slip assembly is set, the tension sleeve is further loaded and tensioned until it parts, thereby separating the setting tool from the packer. The setting tool is then set back down until the setting sleeve once again engages the upper slip assembly and the tubing is pressure-tested.
After the pressure-testing, the setting tool is lifted up until the stinger means is pulled out of engagement with the packer. The tool string is then rotated through a second predetermined number of revolutions to actuate a means for releasing the setting sleeve so that the setting sleeve is free to move in an axial direction relative to the stinger means.
The drill string is once again set down to engage the stinger means with the sliding valve sleeve of the packer to move the sliding valve sleeve downward to open the packer valve.
Using some of the apparatus of the prior art, the entire load set down on the packer is transmitted to the sliding valve sleeve by the stinger means. The sliding valve sleeve in turn transmits that load to a point near the lower end of the packer mandrel.
The packer mandrel itself is supported from the well casing through the upper slip assembly. Therefore, a portion of the packer mandrel, located between the upper slip assembly and the point of support of the valve sleeve, is put in tension. In squeeze packers of this type, the mandrel is generally manufactured from cast iron, and the load-carrying capabilities of cast iron in tension are very much inferior to the load-carrying capabilities of cast iron in compression. The tension loads which can be carried by the cast iron packer mandrel are on the order of 20,000 to 30,000 pounds. In a very deep oil well, having a depth of greater than 10,000 feet, it is very difficult to accurately control the amount of weight which is set down on the packer when actuating the valve sleeve. It often happens with these prior setting tools that an excess amount of weight is set down on the packer causing the packer mandrel to fail due to the excess tension loading.
One apparatus that solves this problem is disclosed in U.S. Pat. No. 4,253,521 to Savage, assigned to the assignee of the present invention. The Savage apparatus provides a setting tool which engages the packer in such a manner that the weight of the drill string is carried by the packer mandrel in compression rather than in tension. A resilient spring means is provided such that the downward force applied to the lower mandrel of the packer must be transmitted through the resilient spring means. The maximum downward force which can be applied to the lower mandrel, and correspondingly to the sliding sleeve of the packer, is equal to a force required to fully compress the resilient spring means. The Savage apparatus also includes an improved releasable locking means between an upper mandrel and a sleeve assembly in the setting tool so that the sleeve assembly may be released to allow free rotational and axial motion of the upper mandrel relative to the sleeve assembly.
The prior art apparatus of Savage is particularly well adapted for setting Halliburton EZ Drill.RTM. squeeze packers, and particularly the Halliburton EZ Drill SV.RTM. squeeze packer with pressure balanced sliding valve therein which is shown in the Savage patent. These packers are illustrated in the Halliburton Services Sales and Service Catalog No. 43, pages 2561-2562. The EZ Drill.RTM. packer is also disclosed in U.S. Pat. No. 4,151,875 to Sullaway, assigned to the assignee of the present invention. The setting tool of Savage works well with these packers, but the setting operation requires rotation of the drill string. Such drill string rotation is not as easily carried out in some conditions, such as when horizontal drilling is being done. In horizontal drilling, it is more difficult to rotate the drill string. Therefore, it is desirable to have a setting tool which is hydraulically rather than mechanically actuated.
A hydraulically activated liner setting device is disclosed in U.S. Pat. No. 4,583,593 to Zunkel et al., also assigned to the assignee of the present invention. This hydraulic device provides for setting a packer by response to differential pressure between the tubing and the well annulus. The Zunkel apparatus includes a ball valve which is closed as the apparatus is run into the hole. Therefore, a fill-up valve means of a type known in the art is positioned above the setting tool in the drill string to allow the tool string to fill. One problem with this apparatus is that it is relatively long and this makes it less well adapted for horizontal drilling conditions. The present invention which includes a flow valve means in a closed position as the apparatus is run into the hole has a built-in fill valve means which internally bypasses the flow valve means. The fill valve means is actuated in response to pressure in the setting tool. The present invention provides a much more compact setting tool than the apparatus of Zunkel, and thus the present invention is particularly well adapted for horizontal drilling conditions.
The Zunkel apparatus also may require dropping a ball down the drill string to the tool under some circumstances. Other known setting tools also involve the use of a ball or a plug which must be inserted in the tool string at the surface. The ball or plug falls to a seat in the setting tool, and pressure is then applied inside the tool string to set the packer. However, dropping balls does no always work satisfactorily in horizontal drilling applications. The present invention does not require the dropping of balls or plugs which is another feature which makes it well suited for horizontal drilling.
Another method of setting packers involves the use of electric wire line in a powder-type setting tool. An electrical charge generated through the line detonates a black powder charge in the setting tool which sets the packer. Wire line setting tools are also not well adapted to horizontal drilling conditions, and thus the present invention provides an improvement over such devices.